In 1935, McInerey received his degree from George Washington University Law School. He taught at the Annapolis Post-Graduate School. As America entered World War II in 1941, McInerney had just assumed command of a destroyer ship, the USS Smith. He participated in the earliest strikes in the Solomons and the Battle of the Coral Sea.

VADM McInerney would move up into more prestigious naval positions. Assigned as Senior Representative Commander of Destroyers in the South Pacific, in March 1944 he was also named Chief of Staff for Commander of Operational Training Command, Pacific Fleet. He assumed command of the battleship USS Washington in June 1945. In October 1946, McInerney reported as Commanding Officer of the Naval Receiving Station, Treasure Island, California. He took command of Cruiser Division Three in March 1949. In January 1950, he became Commander of Amphibious Training Command, Pacific Fleet.